Separation and recovery of naphthenic hydrocarbons from mixtures thereof



Patented Feb. 17, 1953 -.U N IT :ED .STAT/ES lPATEN T OFF ICE '2,628,990 YsiifaitAirioiv 'AD RECOVERY 'or 'NAPH- THENIC `HYDROCARBONS FROM Mm- 'TURES THEREOF Morris lt. Morrow,Baytown-Tex.,assigner, by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., la corporation voi Delaware Application-october 28,1950, serial No. 192,834

(o1. 26o-eee) bons from a mixture'consisting` essentially `of A`napht'lienic and paraiiinic hydrocarbons.` The 4invention has to 'doparticul'arly'with the separation and recovery' of "c'yclohexane from "naphthenic hydrocarbon fractions containing/it.

Thev presentv invention may be 'described' briefly Aas comprising a l'rnethod for separating a naphthen'ic hydrocarbon fraction from va hydrocarbon fraction inthe gasoline boiling range consisting essentially'of naphthenic and paraflinic hydrocarbons. This hydrocarbon fraction is extracted with furfural at a Vte'rnperature in the range between 40 and 300 F. in the'presence of asolvent extract of a naphthenic lubricating oil fraction boiling 'in the range between 570 and 850'Fl and containing a major Y'amount of aromatic's andy naphthenes and a minor amount of parafnns with the naphthenes in excess ofthe aromatics to format least an extract phas'eand a rainate phase.

The two phasesl are separated and naphthenic hydrocarbon is separated from the extract phase by removing solvent therefrom.

In practicing the present invention i-t is' essenitial that a substantially aromatic free hydrocarbon fraction be employedboiling in the gasoline boiling range which lcontains naphthenic hydrocarbons and paraffinic hydrocarbons. If aromatic hydrocarbons are present the naph- Ythenic hydrocarbons will becontaminated with to about 300 F. although'narrowerboilingfractions Inay suitably be employed. For example,

when it is desired to separate cyclohexane from mixtures Vof it with other naphthenic hydrocarbons v'and paraffns, a feed stockl boiling in the rang'e'frorn 30 to '2'0`0"F."shouldbe used.

The solvent extract lemployed in the practice of 'the "present invention is aY solvent extractl of 'naphthenic lubricating voil fraction; solvent extracts `such as furfural extracts, phenol extracts and nitrobenzene'extracts and the like maybe used in 'the practice of vthe present invention.

It is preferred to employ a phenol extract of a naphthenic lubricating oil fraction. For example,` a phenol extract of a' Coastal' lubricating voil distillate 'boiling in the range from 570 to 850 F. may be used satisfactorily. VIt is preferred,

"however, to use a phenol extractof a" Coastal lubricating oil `distiliate` boilingv at a temperature betieen the range of 57 0 and j75n0` which-contains "approximately `30% laromatica" approxivmately 4.0 naphthen'esand approximately 30 "para'lfflns 'As a 'general statement, it `i'nay lbe said that lthe solvent lextract employed "in Ythe practice of the presentiinvention should contain arnajor arnount ofarornatics'and naphthenes rand a rnin'or amount of'pa'rafins with the naphthenes inr excess of the laroinatios The temperature employed in thepresentinvention may range from about 40 to ab'out300 iF. Ordinarily theternperature employedinthe 15l solvent extraction should'not exceed the'boiling point-of the feedstock. AvWhen*cytzlohexa-neis 'separa-ted and recovered the extraction temperature maysuitabiybe in the range from 40 to \200"F.

Inoroler to obtain satisfactryseparation f "naphthenic hydrocarbons in` the present invenftiona furfural to 'feedhydrocarbon'ratio inthe range -from 10:1 to about-:30:1 should be erni'Iher solventextract of anaphthenic lubricatoil fractionjwhich is employed in thepresent invention should be usedV in a ratio of solvent 30` extract to feed hydrocarbon "in the rangeffrom about2:1-toa bout 10:1. est'results are obf-tained'at a ratio of Yaboutf5f1-to '7:1.

`In co'n'dufzting the solvent -extractionoperation it is desirable to-ernploy a vertical solventI extractintower such as well'-knw'nin'the art. 'A "solventextraction l tower having 'f frornabout '5" to '20 extraction stagesrnay suitably `be used in vcon- Y ducting the present-invention. VThe furfural solfvent would be introducedjinto thetp of the verticalextraction'to'wer'and the feed hydrocarbon introduced at about Ythe `center thereof. An 'extractphase 'which would @mamme desirable 'naphthenic' hydrocarbon would be recoveredfrom the b ottomof"the tower while thesolvent extract of theelubricatingfoil fractionwouldbefintroduced at thebottoin of thetower-toexert a Washing `action Non' the VEextract "phase and jthis Awould be removedi as a secondary iiafnatep'hase at a point just below the point where the feed hydrocarbon is introduced into the tower.

This rafnate phase would be separated by distillation into a naphtha fraction which would `beadinixedwith'the fresh feed and returned to the extraction-tower, and a lubricating oil fraction -whiclr'would be recycled with the solvent extract to the bottom of the extraction tower or The primary raffinate phase would beseparated and recovered out of the top of theextraction tower.

Referring to the drawing, numeral II designates a charge line through which a naphthenic hydrocarbon feed containing parans and boiling in the range between 80 and about 300 F. is introduced into the system from a source not shown. Naphthenic hydrocarbon feed flows through line II controlled by valve I2 into a solvent extraction tower I3. Solvent extraction tower I3 is of a type Well known in the art and is understood to include all auxiliary equipment usually associated with solvent extraction towers. Such auxiliary equipment may include means for inducing reflux and internal contacting means whereby intimate contact between the hydrocarbon feed and the solvent is achieved.

Leading into the top of solvent extraction tower I3 is line I4 controlled by valve I5 by way of which furfural is introduced into the system from a source not shown. At a point adjacent the bottom of solvent extraction tower I3 a solvent extract of a lubricating oil such as a phenol extract boiling in the range between 570 and 850 F. is introduced by line I6 controlled by valve I'I. This solvent extract is comprised essentially of aromatics and naphthenes with a minor amount of parans.

The naphthenic hydrocarbon feed contacts the furfural countercurrently and results in the formation of a ra'inate phase containing furfural and parainic hydrocarbons. This rafnate phase is removed from the top of extraction tower I3 by line I8 and is discharged thereby into a solvent stripping zone I9 which is shown as a distillation tower. Distillation tower I9 is provided with a heating means such as coil 20 which allows adjustment of temperature and pressure conditions to allow obtaining of an overhead fraction of parainic hydrocarbons by line 2I while the furfural is recovered by line 22 and may be recycled to line I4. By virtue of introducing a solvent extract of a lubricating oil fraction into the tower I3, a secondary railinate is formed by the washing action of the lubricating oil fraction on the extract phase formed by countercurrent contact of the feed hydrocarbon with the furfural. This secondary raiiinate phase is withdrawn from extraction tower I3 at a point just below the point where the feed hydrocarbon is introduced by line II. This second rafnate phase is withdrawn by line 23 into a stripping zone illustrated by distillation tower 24 which is provided with a heating means illustrated by a coil 25. Conditions of temperature and pressure are adjusted in zone 24 to allow separation of naphthenic and parafnic hydrocarbons which have been washed out of the extract phase by the solvent extract of the lubricating oil fraction. This mixture is withdrawn from zone 24 by line 26 and may be discharged from the system by opening valve 2l, but preferably is recycled to line II by branch line 28 controlled by valve 29. Likewise, there is withdrawn from zone 24 the recovered solvent extract of the lubricating oil fraction by line 30 which may be discharged from the system by valve 3 I, but preferably is recycled to line I6 by branch line 32 containing valve 33 which connects line I6 with line 30.

The extract phase is withdrawn from the bottom of solvent extraction zone I3 by line 34. This extract phase contains naphthenic hydrocarbon and furfural which are separated from each other in stripping zone 35 illustrated as a distillation tower and which is provided with a heating means illustrated by coil 36. Conditions of temperature and pressure are adjusted in zone 35 to allow withdrawal as an overhead fraction of the naphthenic hydrocarbon in a puried form by line 31 while the furfural ls recovered from zone 35 by line 38 for recycling to line I4 as may be desired.

In the description of the stripping zones I9, 24, and 35, it is assumed that these stripping zones are distillation towers, and this term is meant to embrace all auxiliary equipment usually associated with such distillation towers, such as means for providing reflux and internal contacting means to insure intimate contact between liquid and vapors.

In order to illustrate the invention further, a naphthenic hydrocarbon fraction boiling in the range from 30 to 200 F. which contained cyclohexane and which was substantially free of aromatics was charged into a 20 stage vertical extraction tower with furfural being introduced into the top of the tower. The feed hydrocarbon was introduced near the center and it was extracted with the solvent in the presence of a phenol extract of a light coastal lubricating oil distillate .which was introduced at the bottom. A primary rainate was obtained out of the top of the tower. An extract phase containing cyclohexane was recovered from the bottom of the tower while a secondary rainate phase containing the phenol extract was recovered from the tower at a point just below the point where the feed was introduced thereto.

Runs were made in accordance with the foregoing description at temperatures of about to F. In these runs the temperature of the feed was around 86 to 87 F., the temperature of the solvent was in the neighborhood of 72 F. and the temperature of the extract phase containing cyclohexane was about 90 F. The phenol extract was introduced at a temperature of about 87 F.

The yield data, the composition of the feed, primary rainate after removal of solvent, and extract after removal of solvent the phenol extract, as well as the volume of feed, phenol extract and furfural employed are presented in the following table:

t3 It will be seen from the data in the above table that the feed stock was substantially free or" aromatics containing only 2.2 Volume per cent. It will be further seen that the naphthenes were concentrated in both runs in the extract and that the cyclohexane was also concentrated in the extract to a greater extent than that of other naphthenes in the feed stock.

It is understood that a greater concentration of naphthenes may be obtained by adjusting the ratio of urfural to feed to employ furfurai feed ratios in the upper portion or" the range and that further concentration may also be obtained by using additional solvent extraction stages as is weil known to the art.

While it has been stated that the feed stock of the present invention should be substantially aromatic free it is considered that the aromatics should not exceed by volume of the feed stock and preferably should be substantially f absent from the feed stock.

In the foregoing description it is understood that the furfural will be removed from the raiiinate and extract by techniques well known to the art. It is also understood that the secondary raffinate which includes portions oi the phenol extract may be reused in the process.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. A method f r separating a naphthenic hydrocarbon from a hydrocarbon fraction boiling in the range between 80 and 300 comprising essentially oi napht'henic and parainic hydrocarbons which comprises extracting said hydrocarbon fraction with uriural employing a ratio of furfural to hydrocarbon fraction in the range between 10:1 and 30:1 at a temperature in the range between 40 and 300 F. in the presence of a phenol extract of a naphthenic lubricating oil fraction, boiling in the range between 570 and 050 F. and containing a major amount of aromatics and naphthenes and a minor amount of parains with the naphthenes in excess of the aromatics, to form at least an extract phase and a raffinate phase, and recovering naphthenic hydrocarbon from said extract phase.

2. A method for separating cyclohexane from a hydrocarbon fraction containing it boiling in the range between 50 and 200 F. comprising essentially of naphthenic and paraflinic hydrocarbons which comprises extracting said hydrocarbon fraction with furfural employing a ratio of furfural to hydrocarbon fraction in the range of 10:1 to 30:1 at a temperature in the range between 40 and 200 F. in the presence of a phenol extract of a naphthenic lubricating oil fraction, boiling in the range between 570 and 750 F. and

containing approximately 30% aromatics, approximately naphthenes, and approximately 30% paraiiins, to form a first raffinate phase, second raffinate phase and an extract phase, said extract phase containing cyclohexane and said second raiinate phase containing said phenol extract, and recovering cyclohexane from said extract phase.

3. A method in accordance with claim 2 in which the hydrocarbon fraction is extracted with furfural at a temperature in the range between and 90 F. with a ratio of furfural to hydrocarbon fraction of approximately 20:1.

4. A method in accordance with claim 2 in a. which the phenol extract and hydrocarbon fraction are employed in a ratio in the range from 2:1 to 10:1.

5. A method for separating cyclohexane from a hydrocarbon fraction boiling in the range between and 200 F. comprising essentially of naphthenic and paralnic hydrocarbons which comprises extracting said hydrocarbon traction with furfural employing a ratio of furfural to hydrocarbon fraction in the range of 10:1 to 30:1 at a temperature in the range between 40 and 200 F. in the presence of a sufcient amount of a phenol extract of a naphthenic lubricating oil fraction, boiling in the range between 570 and 750 F. and containing approximately 30% aromatics, approximately 40% naphthenes, and approximately 30% parafns, to provide a ratio of phenol extract to hydrocarbon fraction in the range between 2:1 to 10:1 to form a rst and second rainate phase and an extract phase, said extract phase containing cyclohexane and said second rainate phase containing said phenol extract, and recovering cyclohexane from said extract phase.

6. A method in accordance with claim 2 in which the hydrocarbon fraction is extracted with furfural at a temperature in the range between 70 and 90 with a ratio of furfural to hydrocarbon fraction of approximately 20:1 and with a ratio of phenol extract to hydrocarbon fraction of approximately 6:1.

MORRIS R. MORRO-W.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,124,606 Buchel et al July 26, 1938 2,132,359 McCarty Oct. 4, 1938 2,161,567 Gee et al. June 6, 1939 2,330,054 Hibshman Sept. 21, 1943 2,378,808 Sweeney June 19, 1945 

1. A METHOD FOR SEPARATING A NAPHTHENIC HYDROCARBON FROM A HYDROCARBON FRACTION BOILING IN THE RANGE BETWEEN 80* AND 300* F. COMPRISING ESSENTIALLY OF NAPHTHENIC AND PARAFFINIC HYDROCARBONS WHICH COMPRISES EXTRACTING SAID HYDROCARBON FRACTION WITH FURFURAL EMPLOYING A RATIO OF FURFURAL TO HYDROCARBON FRACTION IN THE RANGE BETWEEN 10:1 AND 30:1 AT A TEMPERATURE IN THE RANGE BETWEEN 40* AND 300* F. IN THE PRESENCE OF A PHENOL EXTRACT OF A NAPHTHENIC LUBRICATING OIL FRACTION, BOILING IN THE RANGE BETWEEN 570* AND 850* F. AND CONTAINING A MAJOR AMOUNT OF AROMATICS AND NAPHTHENES AND A MINOR AMOUNT OF PARAFFINS WITH THE NAPHTHENES IN EXCESS OF THE AROMATICS, TO FORM AT LEAST AN EXTRACT PHASE AND A RAFFINATE PHASE, AND RECOVERING NAPTHENIC HYDROCARBON FROM SAID EXTRACT PHASE. 